The rear window defogger system consist of the following components:

Battery positive voltage is supplied through the RR DEFOG fuse in the IP fuse block to the HVAC control assembly. Ignition voltage is supplied through the HVAC fuse in the IP fuse block to the HVAC control assembly. When you turn the ignition to the ON position, and depress the rear window defogger switch. The HVAC control assembly illuminates the rear window defogger indicator and allows battery positive voltage to the rear window defogger. Ground for the rear window defogger is provided by G302.

When you start the engine and press the rear window defogger switch for the first time, the defogger cycle lasts for 10 minutes. Further operation results in 5 minute defogger cycles. The defogger cycle resets to 10 minutes when you cycle the ignition to the OFF position and then back to the ON position.